1. Field of the Invention
This invention relates to a rolling mill apparatus and to a method of shape control of a rolled strip.
This application claims priority from Japanese Patent Application No. 2006-318820, filed Nov. 27, 2006, the contents of which are incorporated herein by reference.
2. Description of Related Art
As a method of correcting the shape (“shape” here means both strip flatness and strip crown) of a rolled strip and a rolled plate (hereinafter abbreviated as a rolled strip) in a rolling mill apparatus, a method is known in which work roll cooling fluids (hereinafter abbreviated as a coolant) at, for example, two different temperatures are selected and sprayed onto the upper and lower work rolls.
In this method, by spraying a high-temperature coolant from a plurality of sprayers arranged parallel to the work rolls, and causing an expansion of the roll diameters through the thermal effect thereof, the strip thickness of the rolled strip is reduced. On the other hand, by spraying work rolls with a low-temperature coolant, which causes contraction of the roll diameters, the strip thickness of the rolled strip is increased. By this means, the shape of the rolled strip is adequately controlled (see Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application No. H 04-197507